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The C20C is the latest member of the new C-series lights from Sunwayman - this time in a 2xCR123A/1x18650 form factor. Very compact, it shares a lot of similarities (and a few differences) from the C10R. Let's go through them …

Manufacturer Specifications:Note: as always, these are only what the manufacturer/dealers report. To see my actual testing results, scroll down the review.

CREE XM-L U2 LED

Soft-contact Side Switch:

One Turbo mode, three modes constant output, hidden Strobe and SOS (below are output and runtime details by using one 2600mAh 18650 battery)

The C20C is definitely very petite for the class. Overall build of the C20C is very similar to the C10R – in fact, from the "neck up" (i.e. the heads), they look identical. The C20C is also not that much larger overall really, as you can see in the comparison pic below.

Here are some detailed pics:

As with all Sunwayman lights, you get the dark gray natural finish anodizing on the C20C. Sunwayman has always had one of the best quality finishes. As always, all labels are fairly small and bright white against the dark background.

Like the C10R, and recent M11R/V11R, Sunwayman has knurling of reasonable aggressiveness on the C20C. With other build elements (ridges, raised areas, etc), I would say overall grip is good.

The body tube is wide enough to take protected 18650 cells, as well as 2xCR123A. I didn't experience any issues with longer cells.

Like the C10R, the C20C is controlled by Sunwayman's new "Smart Switch" - an electronic switch in the head (under a rubber button cover). Switch feel is good for this type of switch, with a definite "click" upon activation. Scroll down for a discussion of the UI.

There is a red LED on the other side of the head from the switch, which serves as a low voltage indicator for the battery. See the UI section below for a discussion.

A clip-on style pocket clip is included with the C20C. While nothing special, it holds onto the light reasonably well for this sort of clip. Note that no clip was included with the C10R.

The light only opens at the tailcap, and screw threads are a thick square-cut and fully anodized for lock-out. I am glad to see Sunwayman restore anodizing after leaving it off the C10R. Screw thread design and number is otherwise similar to the C10R (which differs from the earlier 1xCR123A/RCR lights.

As previously mentioned, the C20C looks virtually identical to the C10R. There is one difference on my sample – the reflector doesn't seem to be quite as deeply seated on my C20C. You can see some evidence for this above – notice the reflection of the bond wires in the upper left-hand size of the reflector? This will likely result in a greater number of beam artifacts around the hotspot.

I've opened up the head to take a look inside:

A few other makes and models have been known to suffer from reflector depth issues (e.g. Zebralight SC600). But as a general rule, it is always easier to raise a reflector than lower it. And in this case, there is nothing I can really do to adjust the height – the plastic insert around the LED seems fully seated. I presume this is therefore just natural variability between samples.

The tail cap allows tailstanding, and a cut-out region to allow you to attach a lanyard through a split ring (while maintaining the ability to tailstand). Why I like these sorts of designs, the aluminum seems very thing on the attachment point of the tail (i.e., I worry it may wear through over time).

User Interface

User interface is similar to C10R, but with an additional constant output mode.

With the tailcap fully-connected, turn the light off/on by the electronic clicky switch. The C20C has two options – click (i.e., quick press and release) for constant on, or press-and-hold for momentary.

As with some of the Spark and Zebralight models that use a similar interface, it may take you a little time to get the timing just right (i.e., too slow on the release, and the light will shut-off, thinking you wanted momentary). But this delayed momentary does give you option to signal with light if you want (i.e., short and long pulses of Morse code).

First time you activate the light, it comes on in Turbo mode. Change output modes by pressing and holding the switch from clicked on. The light will cycle between constant output modes in the following order: Turbo > Hi > Med > Lo, in repeating order. Let go off the switch to select the mode you want.

Light has mode memory, and will retain the last constant output used when turning off and on.

There are "hidden" modes; a strobe and SOS (activated and double-clicking the switch rapidly). On first double-click you get strobe, on second double-click you get SOS. Single click to turn off. Light returns to the memorized constant output when clicked back on.

As this is an electronic switch, a standby current is required (see below for measurements). To reduce the risk of accidental activation, Sunwayman provides a switch lock-out mode. After waiting a minimum of 7 secs with the light off, do a quick click followed immediately by a press-hold. After 1 sec, the light will shut off and cannot be re-activated until the lockout is deactivated. To restore full functioning, double-click the switch followed by a press-hold.

As with all lights with anodized threads, you can also physically lock out the light by a head twist.

There is a secondary red LED on the other side of the head from the switch, which will warn you when a battery is running low. On my C10R, this indicator was set to only work on 1xRCR (by checking for a minimum 3.3V on connection, with a double-flash). The indicator went solid red when the cell reached ~3.05V resting voltage. By that point, output had already dropped to <10% initial output, so it wasn't much of an advanced warning.

On the C20C, the indicator is set to work with only 1x18650. There is no need to check the voltage ahead of time (since that is the lower voltage power source it supports), so there is no flash on connection. The indicator went solid red at ~3.45V resting voltage on my sample. This is a more useful advance indicator of waning battery capacity than the C10R, but is likely already obvious to you by the dropping Hi/Turbo output. Note that it is so low that none of the 2x sources will ever trigger it in practice (i.e. 2xCR123A would be nearly dead, and 2xRCR would have triggered their protection circuits long before then).

For information on the light, including the build and user interface, please see my new video overview:

Video was recorded in 720p, but YouTube typically defaults to 360p. Once the video is running, you can click on the configuration settings icon and select the higher 480p to 720p options. You can also run full-screen.

PWM

There is no sign of PWM that I can see, at any output level – I presume the light is current-controlled, as claimed.

Strobe is a standard "tactical" high frequency strobe, measured at 11.6 Hz (similar to the C10R).

Standby Drain

As the switch is an electronic one, a standby current drain is always present when a battery is installed.

When I first connect my DMM, I measured an initial current of 1.5mA (on an 18650 cell). However, after a few seconds, the stand-by drain dropped to 10.0uA, and remained there stably. This would translate into nearly 30 years before a 2600mAh battery would be drained. It is definitely negligible, and not a concern.

Sunwayman provides a switch lock-out mode that is activated by a quick click followed by a sustained press (see UI section – same as the C10R or T60CS). But unlike the C10R, you can fully lock-out the C20C by a twist of the tailcap (thanks to the anodized threads).

Beamshots:

Time for the white-wall beamshots. All lights are on Max output on an 1x 18650 AW protected cell. Lights are about ~0.75 meter from a white wall (with the camera ~1.25 meters back from the wall). Automatic white balance on the camera, to minimize tint differences.

You can't really see it in the beamshots, but as I expected, the slight depth misalignment of the reflector has resulted in a number of subtle artifacts around the hotspot. Rather than a sharply defined hotspot, you get an overlapping pattern of distortions in the corona. While not severe on my sample, they are noticeable on a white wall.

Looking back at my C10R, I see it also has some evidence of this same effect - it is just more noticeable on my C20C. This not much of a problem in real-life use, but it is noticeable by eye on white walls.

Testing Method:

All my output numbers are relative for my home-made light box setup, a la Quickbeam's flashlightreviews.com method. You can directly compare all my relative output values from different reviews - i.e. an output value of "10" in one graph is the same as "10" in another. All runtimes are done under a cooling fan, except for any extended run Lo/Min modes (i.e. >12 hours) which are done without cooling.

My summary tables are reported in a manner consistent with the ANSI FL-1 standard for flashlight testing. Please see http://www.flashlightreviews.ca/FL1.htm for a discussion, and a description of all the terms used in these tables. Effective July 2012, I have updated all my Peak Intensity/Beam Distance measures with a NIST-certified Extech EA31 lightmeter (orange highlights).

Sunwayman reports a max output on Turbo of 450 lumens. That seems a lot lower than my sample, which I would estimate as >600 lumens (and pretty close to the Eagletac D25LC2). However, once the Turbo mode steps down to Hi, I get ~450 estimated lumens on the C20C (which is a lot higher than the spec 280 lumens).

Output/runtime efficiency is good on my C20C, just as it was for the C10R. The C20C is more heavily driven than I would have expected (based on output specs). Relative mode level spacing appears to be reasonably good, but I would have preferred a lower low.

Note that despite my higher estimated output levels, my actual runtimes are quite consistent with Sunwayman specs (when you take into account the higher capacity battery they used, and the ANSI FL-1 standard time to 10%).

Note the official specs don't make any mention of 2xRCR. However, the voltage range (up to ~8.4V) would suggest it can handle them. And the SWM website does make mention of "16340" (aka RCR) at one point, so I figured it was worth a try.

Potential Issues

Switch timings may take a little getting used to. As you can activate a momentary mode by a sustained press, you must be quick on the press-release for it to register as a click (for sustained on). Other electronic switches (e.g., Zebralights and Spark) can similarly take some getting used to initially.

Due to the electronic switch, a small standby current is always required when a battery is installed. However, this drain was measured at an inconsequential level (i.e. several years before it would drain a battery). As always, I recommend you store the light locked-out when not in use (which is possible here thanks to the anodized threads).

The split-ring/lanyard attachment point in the tail looks thin, and my wear through over time. But this is a design style I like, as it maintains tailstanding.

My sample developed some intermittent flickering in the Turbo mode. It would disappear upon switching down to the lower modes, and may or may not re-appear when switching back to Turbo. Removing and re-installing the battery usually resolved it, and I couldn't reliably elicit it. I suspect it is a circuit issue, as there was no sign of it on the other modes.

Preliminary Observations

As the second member of the new C-series from Sunwayman, the 1x18650/2xCR123A C20C shares many of the same characteristics I described in my recent C10R review. But there are few aspects I prefer to the C20C.

The UI is basically the same, except for the addition of an extra "Turbo" mode on the C20C. This interface gives you a range of options, with blinking modes well "hidden". As with all electronic switches that offer both momentary-on and click-on, it may take you a little while to get used to the exact timings. But once you do, it works consistently.

The physical build is also comparable, with similar styling and the trademark attractive natural anodizing finish from Sunwayman. I am very glad to screw thread anodizing has been restored on the C20C (i.e., so that you can lock out the light). The C20C is quite petite for a 1x18650-sized light as well.

Performance-wise, the C20C is very similar to my Eagletac D25LC2 clicky – both for absolute output levels and relative runtime performance (see output measures earlier in this review). This demonstrates a good current-controlled circuit. Although relative spacing is good, I would still like to see a lower Lo mode (i.e., there is certainly no "Moonlight" level here).

The C20C shares the same head design as the C10R, so should have a comparable beam. However, I found my C20C sample to have more irregularities in the corona around the hotspot (likely due to variability in the exact seating of the reflector). This produces some artifacts around the beam's hotspot (although it is really more a problem on white walls than in real life use). Overall beam pattern is still quite good, and very similar to some of the XM-L-based Zebralights (i.e., relatively large hotspot, with a wide and even spillbeam).

While generally similar to the C10R, I personally prefer the extra touches on the C20C (e.g., the anodized screw threads, pocket clip, extra Turbo mode, larger battery capacity, etc.). It is also remarkably compact for a 1x18650 light. Unless you really need the compact size of the C10R, the C20C may be a better option for overall versatility and extended battery capacity.

(1) How come your SC600 now throws 167 meters, over the old 145 meters?
And the RRT-21 throws 173 meters, over the old 155 meters?
Most of your data has changed?
Edit:
Oh, now you measure them 30 seconds after activation.
That means before, you measured them instantly?

No, I've always measured at 30 secs post activation. The new numbers (in orange highlight) are due to a new NIST-calibrated lightmeter. It is all explained here:

(2) Is there any good reason the Sunway C20C only outputs 620 lumens OTF, rather than the SC600's 780 lumens?

It's a design choice - not everyone chases the max lumens. Of note, the SC600 was always pushing the envelope for max output - but offers several other programmable lower multi-hundred lumen Hi modes to choose from instead. The C20C is a more straight-forward light, with a balanced approach to size and output.

Just updated the review with specific measures of when the red LED battery indicator activated.

On my C10R, this indicator was set to only work on 1xRCR (by checking for a minimum 3.3V on connection, with a double-flash). The indicator went solid red when the cell reached ~3.05V resting voltage. By that point, output had already dropped to <10% initial output, so it wasn't much of an advanced warning.

On the C20C, the indicator is set to work with only 1x18650. There is no need to check the voltage ahead of time (since that is the lower voltage power source it supports), so there is no flash on connection. The indicator went solid red at ~3.45V resting voltage on my sample. This is a more useful advance indicator of waning battery capacity than the C10R, but is likely already obvious to you by the dropping Hi/Turbo output. Note that it is so low that none of the 2x sources will ever trigger it in practice (i.e. 2xCR123A would be nearly dead, and 2xRCR would have triggered their protection circuits long before then).

Hard to say, I haven't tried carrying it on me. It would certainly be a lot easier than the Zebralights, and I used to find those periodically activating on me. I recommend storing it locked out at the switch or tailcap if EDCing on your belt or in a pocket.

2) How many amps on turbo?

I don't typically do tailcap current draws at higher outputs, as I know from experience that the DMM and leads can introduce significant resistance. On more highly-driven lights, this can definitely lead to spurious outcomes (i.e., circuit reacts differently, with lower output, etc.). The only way to ensure reliable current draw measures is at the head, using a bench-top power supply (which I don't have).

3) Any beamshot comparisons with the ZL SC600?

The white wall beamshots are in the review - I don't plan to do outdoor ones. As you tell from the shots, the profile is similar - with the SC600 having a slightly wider spillbeam and a slightly wider hotspot.

The light only opens at the tailcap, and screw threads are a thick square-cut and fully anodized for lock-out.

After examining mine, I tried opening the tailcap using medium strength. Mmmm...maybe it doesn't open this way. I checked the included manual and it showed it in the diagram with the head off and a battery beside it. I really had to tork down on it, but finally it gave. I looked inside and there was blue gunk dried all over the threads. Mmmmm
I read your review closely and noticed you said only the tail opens. Mmmmm. I exerted presure and the cap came loose.
I guess I wasn't supposed to remove the head. What I need to know is if I should leave the head as is or locktite it back down?...or maybe I should just grease up the threads.

I guess I wasn't supposed to remove the head. What I need to know is if I should leave the head as is or locktite it back down?...or maybe I should just grease up the threads.

It shouldn't matter. The head of mine is obviously loctited, but it shouldn't make much of a difference either way. Surprised you had a hard time withe the tailcap on yours, sounds like they loctited both ends on your sample?

Great review!
I really like this SWM, because of its size, but a draw back is the Medium Low, I`m missing really a Low Low.
Specs say 15lm.. but you even measured 27... thats a bit too much for a low..... my taste!

My C20C showed up from Battery junction, light was smaller than I thought, and I like it a lot, thanks for the review. My Callies 3100's fit just fine, and the kids have spent 4 hours in the pool with it last night, no leaks!!!!!!!!!!! It's floody(knew it would be), and maybe we will see a light like this with a G2 LED. No low/low so it will be more of an EDC light vs camping. I've ordered 3 more for family members.

I found that I have to crank the tailcap really hard to make contact. It doesn't matter what kind of battery. I'm a big guy and when I tork down the lid of a peanut butter jar...your not gonna get it open. I think the body could have used an extra thread. I'm afraid I'm eventually going to mash the threads or lose tailcap contact altogether. Is there some kind of very thin washer I could put in the bottom of the tail to effect earlier contact?

LOL, I know, 4 hours in water, no Problem. 4 hours with kids, EXTREME testing. I bought a Pelican light many moons ago, it had a small piece of paper stating: "The guarantee does not cover shark bite, bear attack and children under five" I wish I had framed that!! Pelican people equals smart peoples.

I agree, lower lows needed. It seems like manufacturers do not want to make the perfect all around light so to justify the large line of offerings. If all SWM products had sub 1 lumen modes and a beacon mode I would probably never buy another brand.

Originally Posted by ChibiM

Great review!
I really like this SWM, because of its size, but a draw back is the Medium Low, I`m missing really a Low Low.
Specs say 15lm.. but you even measured 27... thats a bit too much for a low..... my taste!

Judging from my protected 18650 runtimes, it looks like the light will just continue to drain the cells until they are dead. However, there is a very clear drop-off in output long before that happens, which you could use as a signal to recharge the cell.

Question on "working voltage" when using 18650 cells in this light. Per specs above "Working voltage: 4~8.4V". So how is this possible with a 3.7v cell? My concern at this point is running unprotected 18650 cells and this light over discharging past 2.5v min that may ruin the batteries. Any help appreciated..

Question on "working voltage" when using 18650 cells in this light. Per specs above "Working voltage: 4~8.4V". So how is this possible with a 3.7v cell? My concern at this point is running unprotected 18650 cells and this light over discharging past 2.5v min that may ruin the batteries. Any help appreciated..

The working voltage range is to indicate that 2xCR123A and 2xRCR will work in the light, in addition to 1x18650.

The issue of over-discharge is different. In this case, you can tell from the runtimes that 1x18650 either drops-down or rapidly falls off in output as the cell nears exhaustion. So you could probably use unprotected cells fairly well (on Med-Hi) if you wanted to - just make sure to charge the battery by the time you notice a drop-off in output.

The working voltage range is to indicate that 2xCR123A and 2xRCR will work in the light, in addition to 1x18650.

The issue of over-discharge is different. In this case, you can tell from the runtimes that 1x18650 either drops-down or rapidly falls off in output as the cell nears exhaustion. So you could probably use unprotected cells fairly well (on Med-Hi) if you wanted to - just make sure to charge the battery by the time you notice a drop-off in output.

OK I get that you can tell when to change, but my concern with a light of this type is if accidental power on occurs (very possible with this type of switch), and it goes undetected...will it drain the battery an ruin the cell? Since I haven't bought the cells yet, I could get protected, but prefer the unprotected for cost and possible fit reasons. So, bottom line, is there a low voltage cutoff in the light?

Sunwayman use one 2600mAh 18650 battery. Can i use one battery like this below or 3400mAh?

Panasonic 18650A

Capacity: 3100mAh

Recommended Max Discharge: 6.2A (2C)

Full charge: 4.2V

Nominal voltage: 3.6V

Cut-off: 2.5V

The reason I ask is I don't know the technical specs of the light. Is it better to have the possible higher retained voltage of the 2600 mAh battery. Or the possible higher retained amperage from the 3100mAh or 3400mAh battery?

OK I get that you can tell when to change, but my concern with a light of this type is if accidental power on occurs (very possible with this type of switch), and it goes undetected...will it drain the battery an ruin the cell? Since I haven't bought the cells yet, I could get protected, but prefer the unprotected for cost and possible fit reasons. So, bottom line, is there a low voltage cutoff in the light?

Thank you for the help.

Kevin

Kevin, I'm certainly 'on board' that it's interesting to know if it has low voltage cutoff or not but the reasons that you're citing for the possibility of running unprotected cells are quite trivial. It seems that this light accepts 3100 & 3400mAh cells. No fit problems thus far so count that as a non-issue . 18650 protected cells are available for as little as $7-8 a copy. What does an unprotected 18650 cell cost....a dollar less? I think the safety benefits far outweigh any perceived objections.

Without a bench top / power supply, I don't think Selfbuilt has any way to test whether this light possesses a low voltage cutoff without actually running a non-protected 18650 in the light. Perhaps you could send him one to possibly ruin.